Difference between bi- and di-

Discussion in 'Linguistics' started by arfa brane, Jul 22, 2015.

  1. arfa brane call me arf Valued Senior Member

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    My understanding is that bi- as a prefix means more or less "double" or "two of", whereas di- signifies "between two things", as in the diameter being between two halves of a circle, a digonal angle being that between two edges of a n-gon, and so on.
     
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  3. Daecon Kiwi fruit Valued Senior Member

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    Maybe bi- means double and di- means halve?
     
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  5. sideshowbob Sorry, wrong number. Valued Senior Member

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    "Bisect" = halve.
     
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  7. arfa brane call me arf Valued Senior Member

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    Halve = divide into two separate parts. I'm pretty sure the di- prefix (not dis-) implies some kind of separation (diverge, digress), but bi- implies "two", "twice".

    Humans are sexually dimorphic as all mammals are, we aren't bimorphic. I take that to mean we are separated or made distinct by our gender, for instance. If humans were bimorphic, there would be two species or subspecies. If we were sexually bimorphic, well, you work it out.
     
  8. sideshowbob Sorry, wrong number. Valued Senior Member

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    If humans were bimorphic, there would be two morphs or submorphs.
     
  9. Sarkus Hippomonstrosesquippedalo phobe Valued Senior Member

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    The prefixes, as far as I know, are synonymous in meaning.
    The difference is in origin: bi- is from the Latin, di- is from the Greek, and the one we use is thus dependent upon the root word. There may be exceptions but I can't think of any right now.

    There are some words of Latin origin that do technically start with di- (as in dissect) but the etymology of these words is likely to be dis- which means "apart", rather than the Greek di- meaning "two", "twice", "double" etc.
     
  10. Fraggle Rocker Staff Member

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    Yes, that's right. Thanks for answering that question before I had a chance to catch up.

    Greek di- is a cognate of Latin due, Irish , Proto-Germanic twa, Slavic and Sanskrit dva, etc. It clearly goes all the way back to Proto-Indo-European.
     
  11. arfa brane call me arf Valued Senior Member

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    Nonetheless, I maintain that modern usage puts words with a di- prefix into a category that generally means "separate" or "separated in two".

    Whereas, in modern usage bi- words are in a category meaning "two of". Hence, angle bisection means there are two (equal) angles. The word dissect means to cut from or out of.

    And if we have two genders, why aren't we bimorphic in that context? Why are we sexually dimorphic (i.e. gender-separated).
    If we were sexually bimorphic, we would be both male and female, ne c'est pas? Or, someone born with both genders would be (this happens occasionally).
     
  12. Sarkus Hippomonstrosesquippedalo phobe Valued Senior Member

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    That's because you are confusing words with the prefix of di- (meaning two) and the prefix of dis- (meaning apart). The comparison in question is between the prefix di- and bi- so you need to be sure you are comparing apples with apples, and not with bananas.
    Because dissect comes from the Latin dis- (apart) and secare (to cut). And not di- (two).
    The reason is simple: morphe is a Greek word meaning form or shape. Hence it will take the Greek prefix rather than the Latin - hence dimorph rather than bimorph.

    Your theory is simply wrong, I'm afraid. Hopefully the above explains.
    If in doubt, list all words that you think have the root di- and bi- and we should see that both roots mean the same thing: "two", "twice", "double" etc, and that the one we use depends on the origin of the root word.
    And even then you have to be aware that Latin words may have originally stemmed from the Greek.
    E.g. Dipole - which seems to come from di- and polus, so a Greek prefix and Latin root, but the Latin actually comes from polos, the Greek.

    If there is any trend it is that scientific words tend to use the Greek (because they take their technical words primarily from Greek rather than Latin, although medicine uses Latin rather than Greek) hence physics and chemistry would use dipolar, medicine would use bipolar (noting that the root word can be either Latin or Greek, hence there is still consistency with di- for Greek, bi- for Latin), dioxide rather than bioxide etc.

    But do not confuse the Greek di- with the Latin dis- as they mean different things, and this might well be where your theory arises from.
     
  13. arfa brane call me arf Valued Senior Member

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    Well, maybe explain why converge and congress have the respective antonyms: diverge and digress.

    I agree that there are words that have either a bi- or di- prefix that appear to be about two things: a dipole switch has two poles, someone with bipolar disorder switches between two states.
    Explain what a bimorphism is then. Or are you saying biologists only use the greek version?

    Let me put all that another way: the Greeks had di- as a prefix and morphe, later the Romans used bi- as well. Today, biologists use the words bimorphism and dimorphism in quite distinct ways, they do not mean the same thing. I'll call that example my poster child.

    Let's see if we can move on from this one.
     
    Last edited: Jul 25, 2015
  14. Sarkus Hippomonstrosesquippedalo phobe Valued Senior Member

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    Sure: you need to understand the etymology of the words. All the words are of Latin origin. Con- means with / together, and the di- is actually the shortening of dis meaning apart. Our words actually come direct from the Latin divergere and digredi, digressus. I.e. they Latin folk had already shortened the word dis when used as a prefix, but the prefix is from dis meaning apart, not di meaning two.

    You need to appreciate that the prefix may look and be spelled the same way, but they have different actual roots and therefore different meanings.
    A bimorph is a cantilever with a metal and a pizoelectric layer. At least that's how I understand it.
    My guess would be, as is the way with our language, since the more usual word (in this case dimorph) already existed and had a specific meaning, they coined a new one to mean something specific in their own area. This would be a case of an exception, not the rule.
    I believe bimorph is a modern coinage, not from a Latin word. The Latin equivalent of morph (shape or form) would be... unsurprisingly... forma.

    I don't disagree that words beginning with di- (as you have exampled) more often than not have the meaning of "apart", but then you're not comparing apples with apples as you should be when looking at bi- or di-, because those words that start with di- with the meaning of "apart" are from the prefix of dis (apart) and not di- (two of).
     
  15. arfa brane call me arf Valued Senior Member

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    The diameter of a circle is one thing, not two. Would this have originally been a disameter? Or, perhaps the Greeks started all the confusion when they dropped the "s" on that one.

    What about divide? Obvious Greek etymology but doesn't have any "two-ness", because you can divide something into any number of separate parts.

    Without the "s" to inform you, you have only modern usage.
     
  16. Sarkus Hippomonstrosesquippedalo phobe Valued Senior Member

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    Diameter comes from the Greek words dia- meaning across, and metron meaning measure.
    Again, you are not looking at the original roots but simply working on the English "di-" as if this should be directly comparable to "bi-" in all instances. It isn't - but if you want to compare apples with apples then the explanation previously provided should be sufficient: the general rule is that the prefix is of the same language as the root word.
    Divide is actually from the Latin dividere - meaning "to force apart" or "to share" and is a combination of dis (apart) and videre (to separate, although also means more commonly to see).
    If you have an understanding of the etymology, it is not too difficult.
    If your intention is to argue that English words beginning with "di-" don't necessarily mean "two" or "twice" etc, then yes, you are correct: we have words from many different languages that start with di-, and the "di-" means different things. But if the question is when to use bi- or di- the question must surely relate to when those prefixes mean the same thing (i.e. "two"). And the general rule previously explained holds.

    What you are doing is merely giving examples when the di- is not equivalent in meaning - which is explained by the di- being from a different original word (as in dis). So, do you have any examples where you're actually comparing apples with apples, or are you just going to continue to show how bananas are not apples?
     
  17. arfa brane call me arf Valued Senior Member

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    This "general rule" you mention doesn't seem to apply to those two biological terms (bimorphism, dimorphism), which have quite definite and as I mentioned distinct meanings. According to your "rule" they are the same word.
    Can you explain what might have happened to the rule with this example, or is it some kind of exception--the biologists should have checked the dictionary more closely?
     
  18. Sarkus Hippomonstrosesquippedalo phobe Valued Senior Member

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    I already have provided an explanation as to how bimorphism as a word may have arisen. Refer to post #11. Basically it may have been that the term dimorphism was taken that meant something different than they wanted, so they coined a new one.

    As for the meanings, you haven't actually provided any other than stating that they are different. Care to do so, please, just so I can be sure you're not making it up - assuming that you're referring to a different "bimorph" than the one I previously referred to (which is not really to do with biology)? I am not aware of any "bimorphism" in biology (and a search of t'internet doesn't seem to shed any light) - but it isn't a subject I know too much about, although I have heard of "biomorphism".

    And as for all general rules, there are bound to be exceptions. Are you hanging your argument on an exception?
     
  19. arfa brane call me arf Valued Senior Member

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    In Biology, a dimorphism is generally something that means having two different forms, but in the same species as in the example of two genders. A bimorphism also generally means having two forms, but expressed in individuals of the same species, as in being both genders (if that's the context). Sexual dimorphism/bimorphism is an example of a more general terminology.

    The meaning of bimorphism is the expression of the same thing (organ) in two ways, but in individuals. Like say a plant that has two kinds of flower or leaf.
     
    Last edited: Jul 25, 2015
  20. Sarkus Hippomonstrosesquippedalo phobe Valued Senior Member

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    And there you have your explanation for the exception to the general rule: two similar notions (both involving two morphologies/forms) but distinct from each other... thus when the usual word (Greek prefix + Greek root) was already taken for one of the ideas, the subsequent idea coined the other word (Latin prefix + Greek root) so as to avoid confusion.

    Simples, really.

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  21. arfa brane call me arf Valued Senior Member

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    Sure, makes sense if you consider how long biologists have been using those words (I'd guess more than a century).

    But there it isn't, so to speak. The thing is, Biology ignores the "normal rules" you mention, it makes the prefixes distinct, it means things have changed. You claim this is a single exception to a more general rule that makes bi- and di- have the same meaning. I don't think that can be true.
    If you know anything about languages, you should know that they change.

    Ok, it's one example. Does that mean there aren't any others? I would think not.

    Maybe I should compare the Greek di-, dia-, dis-, with Latin bi- bio, bis, or something.
     
  22. Sarkus Hippomonstrosesquippedalo phobe Valued Senior Member

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    I'm not saying it's the only exception. It's certainly one you have come up with, but there are undoubtedly more.
    But the general rule is as I have mentioned previously. When a new word is sought due the existing words being taken, they may go against the general rule. Sciences are more likely to do this than other areas, because they probably have a greater need for words that have specific meaning while being similar but distinct from what the existing word describes. Possibly biology is more prone to this than others, I couldn't say. But they would still be exceptions to the general rule.

    I know something about Latin and somewhat less about Greek (zip about other root languages), and while some things do change (esp. the meaning of specific words), the general rules such as mentioned have been in place for rather a long time, and still hold as general rules. But yes, exceptions do and will exist.

    If you're going to compare words with other roots, make sure you know what the root means, and at least make sure you're comparing apples with apples.

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  23. arfa brane call me arf Valued Senior Member

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    My Collins Latin-English dictionary has the following:

    biceps: two-headed.
    biclinium: reclining couch for two.
    bicolor: two-colored.
    ...
    biformatus: with two forms.
    ...
    bilinguis: bilingual.
    bilix: double-stranded.
    bipartitus: in two parts or directions.
    ...
    biremus: two-oared.
    bis: twice.

    Then we have:

    diducere: separate, open up.
    digerere: divide, distribute.
    ...
    dimidius: half
    diota: two-handled wine jar (taken from the Greek as is)
    dirimo: part, divide, interrupt.
    diruere: scatter.
    ... (lots of words starting with dis- that don't seem to be related to "two" or "apart").
    finally
    divortium: separation, divorce by consent.
     

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